I take 10 mg zocor (simvastatin) 20 mg prozac every morning after a few hours of being up blood pressure drops to 90/58 then after a few more hours goes back up. ?

Not clear: Prozac (fluoxetine) is not known to significantly interact with simvastatin so it is not clear that is the cause and you may have morning hypotension for other reasons. You may simply be dehydrated in the morning. However, if you are symptomatic with this morning low blood pressure or if persists I recommend seeing your health care provider for an evaluation.

See doctor: Do you feel faint or dizzy with blood pressure changes? See your pcp to find cause, including possible side effects from meds, although abrupt blood pressure changes are unlikely from Prozac (fluoxetine). I hope this helps. Best wishes.